1. Field of the Invention
The present invention generally pertains to power transmissions systems, and more particularly to a system in which power is transferred from a power source via a rotatable screw member to a chain or other flexible drive member, such as a continuous drive belt.
2. Description of the Related Art
It is known within a variety of fields to use a drive sprocket to transfer rotational power from a power source, such as a motor, to a chain or other belt-type drive component. One example of this type of system is the drive system on a military tank in which power is transferred through a gear box to a drive sprocket which in turns drives the tracks of the tank. A similar example, but on a much more miniaturized scale, can be found in the oil and gas industry, in which downhole tractors include tracks that are driven by a drive sprocket. An example of a downhole tractor is shown in U.S. Pat. No. 4,670,862. Downhole tractors of this type are typically used to convey logging devices and other devices in horizontal and highly-deviated wells. As will become apparent from the following description and discussion, however, the present invention, which is also directed to systems for transferring rotary motion to an endless flexible device, overcomes the deficiencies of the previous devices and constitutes an improved and more efficient drive system.